Liquid crystal integrated circuit and method to fabricate same

ABSTRACT

A structure includes a first substrate having a first surface and a second substrate having a second surface facing the first surface; liquid crystal material disposed between the first and second surfaces; a first upstanding electrode disposed over the first surface and extending into the liquid crystal material towards the second surface; and a first planar electrode disposed upon the first surface and electrically connected with the first upstanding electrode. The first planar electrode at least partially surrounds the first upstanding electrode. A combination of the first upstanding electrode and the first planar electrode forms at least a portion of a pixel of a liquid crystal display. Various methods to fabricate the structure are also disclosed.

TECHNICAL FIELD

The exemplary embodiments of this invention relate generally tosemiconductor devices and fabrication techniques and, more specifically,relate to liquid crystal (LC) devices, such as those used in LC displays(LCDs), and to processes for fabricating such devices and displays.

BACKGROUND

LCDs currently dominate display technology for television, computermonitors and handheld mobile devices. The demand for wide viewing angle,higher brightness, high resolution and fast response time displaysincreases as graphic and video applications expand into such devices.LCDs utilize an electric field to change the direction of the liquidcrystal molecules and to modulate the optical output of the device.

SUMMARY

In a first aspect thereof the exemplary embodiments of this inventionprovide a structure that comprises a first substrate having a firstsurface and a second substrate having a second surface facing the firstsurface; liquid crystal material disposed between the first and secondsurfaces; a first upstanding electrode disposed over the first surfaceand extending into the liquid crystal material towards the secondsurface; and a first planar electrode disposed upon the first surfaceand electrically connected with the first upstanding electrode, thefirst planar electrode at least partially surrounding the firstupstanding electrode, where a combination of the first upstandingelectrode and the first planar electrode forms at least a portion of apixel of a liquid crystal display.

In a further aspect thereof the exemplary embodiments of this inventionprovide a method to fabricate electrodes for a liquid crystal display.The method comprises providing a substrate having a surface; coating thesurface with a dielectric material; patterning the dielectric materialto form a plurality of upstanding first electrode structures each havinga height that exceeds a width; coating the upstanding first electrodestructures and the substrate surface between upstanding first electrodestructures with an electrically conductive material; and removing theelectrically conductive material from between two adjacent upstandingfirst electrode structures so as to retain a portion of the electricallyconductive material upon the substrate surface thereby formingsubstantially planar second electrode structures individual ones ofwhich are electrically continuous with the electrically conductivematerial that coats an associated upstanding first electrode structure.

In another aspect thereof the exemplary embodiments of this inventionprovide a method to fabricate electrodes for a liquid crystal display.The method comprises providing a substrate having a surface; depositinga first layer comprised of an electrically conductive material on thesurface; depositing a second layer comprised of photoresist on the firstlayer; selectively removing first portions of the second layer to leavesecond portions, each second portion being located at a position wherean electrode is to be formed; removing those portions of the first layerunderlying the second portions of the second layer, and removing thesecond portions of the second layer, leaving on the surface upstandingfirst electrode structures each having a height that exceeds a width.

In yet another aspect thereof the exemplary embodiments of thisinvention provide a method to fabricate electrodes for a liquid crystaldisplay. The method comprises providing a substrate having a surface;depositing a layer comprised of photoresist on the substrate surface;opening apertures through the layer to expose the substrate surface atlocations corresponding to positions where an electrode is to be formed;filling the apertures with an electrically conductive material; andremoving the layer of photoresist leaving on the surface upstandingfirst electrode structures comprised of the electrically conductivematerial, each upstanding first electrode structure having a height thatexceeds a width.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of a conventional multi-domain verticalalignment (MVA) mode LCD.

FIG. 2 shows an example of a conventional two domain in-plane switching(IPS) mode LCD.

FIG. 3 shows an example of a conventional fringe field switched (FFS)mode LCD (right side, contrasted with the conventional IPS mode LCD,left side).

FIGS. 4A-4E, collectively referred to as FIG. 4, show an example of afirst process (PPLK coated with ITO) suitable to fabricate finelectrodes.

FIGS. 5A-5E, collectively referred to as FIG. 5, show an example of asecond process (PPLK coated with ITO) suitable to fabricate finelectrodes and associated planar electrodes.

FIGS. 6A-6C, collectively referred to as FIG. 6, show an example of athird process (nano-imprinting) suitable to fabricate fin electrodes.

FIGS. 7A-7E, collectively referred to as FIG. 7, show an example of afourth process (patterned photoresist) suitable to fabricate finelectrodes.

FIGS. 8A-8E, collectively referred to as FIG. 8, show an example of afifth process (lithography and liftoff of ITO ink) suitable to fabricatefin electrodes.

FIG. 9A shows a fin (upstanding) electrode as fabricated by theprocesses of either FIG. 4 or 5; FIG. 9B shows a variation of the finelectrode structure where the fin electrode sidewalls are tapered so asto enhance coverage of the sidewalls with the electrical conductor; andFIG. 9C shows several further variations that beneficially increasesidewall coverage while also providing a larger aperture ratio.

FIG. 10A shows an arrangement of inter-digitated, both pixel and common,fin electrodes formed on the same substrate; FIG. 10B shows anembodiment where negative (common) fin electrodes are formed on a firstsubstrate and positive (pixel) fin electrodes are formed on an opposingsecond substrate; and FIG. 10C is a top view of the fin electrodes ofeither FIG. 10A or 10B where the fin electrode is shaped to formmultiple domains.

FIG. 11 shows an example of a fringe field switch (FFS) mode LCD where acommon electrode is an electrode disposed beneath the pixel finelectrodes and separated therefrom by a dielectric layer.

FIG. 12 (FIG. 12A (top view) and FIG. 12B (side view)) shows anembodiment where the fin electrode is used in the MVA mode, where thecommon electrode is disposed on a first substrate and the fin pixelelectrode is combined with a planar electrode.

FIGS. 13A and 13B show an embodiment of the fin electrode and the planarelectrode used in an electrically controlled birefringence (ECB) mode ofoperation.

FIGS. 14A and 14B show two different examples of shapes of a combinedfin electrode and planar electrode, while FIG. 14C shows examples ofauxiliary electrodes that can be used with either or both of the shapesof FIGS. 14A and 14B (or other shapes/geometries of the fin electrodeand the planar electrode).

DETAILED DESCRIPTION

There are basically two types of LCD electrode configurations. A firstconfiguration can be considered as being somewhat analogous to aparallel capacitor, where planar electrodes are deposited on front andback glass substrates that sandwich a layer of LC material. In thisconfiguration the electric field between electrodes is approximatelyperpendicular to the glass substrates. Twisted nematic (TN) and verticalalignment (VA) liquid crystal modes use this configuration. The electricfield operates to switch LC modules out of the plane (TN) or into theplane (VA) of the substrate. The second type of LCD electrodeconfiguration is referred to as an in-plane switching (IPS) mode, whereboth positive and negative electrodes are fabricated on the samesubstrate. The in-plane electrical field that is generated rotates LCmolecules parallel to the plane of the substrates and thereby causes avisually apparent effect.

One basic requirement for a LCD is to have a small non-switchable LCtransition area (between LCD pixels or picture elements). The gapbetween the pixel electrode, the thin film transistor (TFT) area that iscovered by a black matrix, and the top of the in-plane electrodes arethose areas within which LC molecules are not switchable to the desiredorientation. In addition, since the LC molecules are typically coupledtogether by long range forces the distortion due to the presence of afringe field can typically be larger than the physical dimensions of thegaps between the electrodes. When LC molecules cannot be switched to thedesired orientation the image quality, such as brightness, contrast, andviewing angle, is degraded. This is especial true for high resolutiondisplay devices.

Many technologies exist for making wide-viewing angle LCDs. In additionto the commonly used twisted nematic (TN) LCDs there are other LCDmodes, such as the multi-domain vertical alignment (MVA) mode, a pi-cellmode and the in-plane switching (IPS) mode. A common approach toenlarging the viewing angle of an LCD is to use a multi-domaintechnology, in which the liquid crystal molecules within a pixel areforced to deform to more than one configuration to compensate forbirefringence anisotropy.

Referring to FIG. 1 a multi-domain VA mode is shown. The VA mode useshomeotropic (vertical) alignment material for an alignment layer,anti-parallel rubbing with a small pre-tilt angle (LC molecules aretilted with a small angle away from the substrate normal direction) forthe alignment layer, and negative dielectric anisotropic LC material.Due to the presence of the homeotropic alignment material and the use ofthe anti-parallel rubbing, in the field off state the liquid crystaldirector is almost perpendicular to the substrate surface with a smallpre-tilt angle (away from the substrate normal). This makes the LCmaterial have virtually no effect on the incident light hitting thedisplay from a normal incident angle. However, the effectivebirefringence increases rapidly and thus can result in a degradation ofimage quality in off angles (angles away from the substrate normal). Theprotruding structures or slits in the electrode are used to assist theLC molecules to tilt into different directions to compensate for thebirefringence variations.

FIG. 2 shows an example for a two domain IPS mode. In this example theinter-digitated in-plane electrodes have a chevron shape so that thedirector of the LC molecules is switched to directions to improve theview angle characteristics.

The electrodes in such LCDs are thin film electrodes of a few thousandsof Angstroms thickness formed on one substrate (IPS mode) or bothsubstrates (other modes). The fringe field and protruding structures arethe elements that force the liquid crystal director into differentdomains, where protrusions introduce an initial pre-tilt and fringefield that provides an additional inclination in the field on-state tofurther assist the control of the LC director. Since the electro-opticaleffect of LC material is determined by orientation of the liquid crystalmolecules in the entire display (or pixel), the accurate engineering ofthe LC director in any state, and in the LCD, is important to improvingthe viewing angle.

The fringe field generated by slits in planar electrodes is basicallyless than adequate to provide an improved control of the LC director.This problem is even more aggravated in the IPS mode, where theelectrodes are on one substrate and the bulk liquid crystals, especiallynear the opposite substrate, are switched by a fringe field.Furthermore, the presence of a weak electrical field also implies aslower response time.

FIG. 3 shows an illustration of electrode configurations for the IPSmode and the fringe field switch (FFS) mode, where the FFS mode can beconsidered as a modified IPS mode. As opposed to the use ofinter-digitized electrodes in the IPS mode, in the FFS mode a counterelectrode is moved beneath comb electrodes that are separated by a layerof dielectric. One advantage of the FFS mode is a presence of a strongerfringe field and an improved control of the LC director resulting in anincreased optical throughput and faster switching. However, the fringefield is still the dominant driving force, and control of the LCdirector remains limited.

The embodiments of this invention provide a display with non in-plane(non-planar) electrodes. The use of non-planar electrodes implies thatthe height of the electrodes is comparable to or larger than the widthof the electrode. The use of non-planar electrodes further implies thatthe shape/geometry of the electrode can be other than a simple sheetwith protruding bumps. In the use of the non-planar electrodes there canbe significant portions of electrodes out of the plane of the substratethat provide modification to the electrical field generated byconventional planar electrodes.

In certain embodiments of this invention a photo-patternable lowdielectric constant (low-k) (PPLK) material can serve as both aphotoresist material and as a permanent on-chip insulator, afterpatterning and curing. In certain embodiments of this invention highaspect ratio structures are formed by patterning PPLK material utilizinga single exposure process. After patterning of the PPLK material, thepatterned PPLK material can be converted into a permanently patternedon-chip material by curing to form a PPLK structure. A thin filmelectrode material can then be used to coat over the PPLK structure andother features to form LCD pixel electrodes. For convenience suchnon-planar electrodes can be referred to as “fin” electrodes.Non-limiting examples of PPLK materials include, but are not limited to,some organic polymers.

An example of a first process suitable to fabricate fin electrodes isdepicted in FIGS. 4A-4E, collectively referred to as FIG. 4. In FIG. 4Aan electrically insulating substrate, such as a glass substrate 10, isprovided with thin film transistors, wiring and connecting viaspre-farmed where needed by the requirements of the LCD to be fabricated.In FIG. 4B a layer 12 of PPLK material is deposited by any suitabletechnique, such as a spin-on process, to a desired thickness. Anoptional anti-reflective coating may be deposited on the substrate 10prior to the deposition of the PPLK material when necessary. In FIG. 4Cthe PPLK layer 12 is patterned to conform to a desired electrode pattern12A, such as by optical lithography or other patterning techniques.Suitable but non-limiting optical lithography processes include I-line,DUV (e.g., 248 nm, 193 nm), EUV, E-beam and laser direct write, contactprinting, as well as nano-imprint processes. In FIG. 4D an electricallyconductive material, such as an indium-tin-oxide (ITO) layer 14 isapplied. Suitable ITO coating techniques can include, for example,sputtering, thermal evaporation and spray pyrolysis. In FIG. 4E theunnecessary ITO between electrodes is removed such as by the use of adirectional ITO etch, e.g., a reactive ion etch (RIE). This can be a dryetch (RIB) process based on, for example, hydrocarbon, H₂, O₂, Ar, etc.The use of a wet etch is another option for ITO removal. The end resultis the formation of ITO-coated PPLK patterns as the fin electrodes 16.

An example of a second process suitable to fabricate fin electrodes andassociated planar electrodes is depicted in FIGS. 5A-5E, collectivelyreferred to as FIG. 5. The processes shown in FIGS. 5A-5D can beessentially identical to the processes shown in FIGS. 4A-4D. However, inFIG. 5E not all of the ITO material between the final electrodes 16 isremoved thereby forming substantially planar electrodes 18 disposedhorizontally between the vertically disposed electrodes 16. The unwantedITO material can be removed, as in FIG. 4, e.g., a dry etch (RIE)process based on, for example, hydrocarbon, H₂, O₂, Ar, etc. The use ofa wet etch is another option for ITO removal. The end result is theformation of ITO coated PPLK patterns as the fin electrodes 16 andassociated planar electrodes 18. The thickness of the planar electrode18 will generally be a fraction (e.g., less than 50%, or less than 25%,or less than 10%) of the height of the associated fin electrode 16. Theindividual planar electrodes 18 can be seen to be electricallycontinuous with their associated fin electrode 16.

An example of a third process suitable to fabricate IPS fin electrodesis depicted in FIGS. 6A-6C, collectively referred to as FIG. 6. In FIG.6A the glass substrate 10 is provided with thin film transistors, wiringand connecting vias pre-formed where needed. In FIG. 6B an ITO inkpre-pattern 22 is printed by a suitable direct patterning technique. Thesuitable patterning techniques include, but not limited to, directpatterning of ITO ink by nano-imprint, inject printing or other contactprinting techniques. The ITO ink can be, for example, a solution ormixture or suspension of ITO, a polymer binder and a solvent. Theresolution range of the ITO pre-patterns 22 are, for example, about 10nm to about 10 μm. In FIG. 6C the ITO ink is fired (thermally processed)to form ITO electrodes 24, such as by a thermal process conducted atabout 500° C.-600° C. for about 30 minutes to about 120 minutes in air,N₂, or He gas (as non-limiting examples of temperatures, times andatmospheres). Note that depending on the characteristics of the ITO inkthat more than one printing operation can be used to build up the ITOpre-patterns 22 to the desired thickness that will correspond to theheight of the completed ITO electrodes 24.

Note also in this embodiment that planar electrodes, similar to theelectrodes 18 as in FIG. 5, can be deposited prior to the deposition ofthe ITO ink 20, and the fin electrodes 24 can then be subsequentlyformed upon the planar electrodes.

An example of a fourth process suitable to fabricate IPS fin electrodes,using lithography and an etch (wet or dry) is depicted in FIGS. 7A-7E,collectively referred to as FIG. 7. In FIG. 7A the glass substrate 10 isprovided with thin film transistors, wiring and connecting viaspre-formed where needed. In FIG. 7B an ITO film layer 30 is formed to adesired thickness. The ITO film layer 30 can be deposited by, forexample, sputtering, thermal evaporation and/or spray pyrolysis. In FIG.7C a layer 32 of photoresist is applied over the ITO film layer 30. InFIG. 7D patterns 32A (e.g., apertures such as trenches) are formed inand through the resist layer 32, the patterns 32A being formed where finelectrodes are desired to be formed in FIG. 7E. The patterns 32A can beformed by I-line, DUV (248 nm, 193 nm), nano-imprint, contact printing,contact printing, laser or e-beam direct write and the like. In FIG. 7Ethe patterns 32A are transferred into the ITO film layer 30 to form ITOelectrodes 34. The pattern transfer process can include the use of a wetetch such as one using an HCl etchant or a dry etch (RIE) such as oneusing hydrocarbon, H₂, O₂, or Ar.

As another embodiment the blank ITO film layer 30 can be applied by theuse of ITO ink. In this case then ITO electrodes 34 can be fired, as inthe embodiment of FIG. 6, to form the completed ITO fin electrodes 34,or the ITO film layer 30 could be fired prior to patterning.

Note in this embodiment that the planar electrodes, similar to theelectrodes 18 as in FIG. 5, can be deposited prior to the deposition ofthe ITO film 30, and the fin electrodes 34 can then be subsequentlyformed upon the planar electrodes.

An example of a fifth process suitable to fabricate IPS fin electrodesusing lithography and a liftoff process is depicted in FIGS. 8A-8E,collectively referred to as FIG. 8. In FIG. 8A the glass substrate 10 isprovided with thin film transistors, wiring and connecting viaspre-formed where needed. In FIG. 8B a layer 40 of photoresist isdeposited in the surface of the substrate 10. In FIG. 8C patterns 40A(apertures such as trenches) are formed in the resist layer 40, thepatterns 40A being formed where fin electrodes are desired to be formedin FIG. 8E. The patterns 40A can be formed by Mine, DUV (248 nm, 193nm), nano-imprint, contact printing, laser or e-beam direct write andthe like. In FIG. 8D ITO ink 42 is deposited so that it at least fillsor partially fills the patterns 40A formed in the photoresist 40. InFIG. 8E the ITO ink 42 is fired to form ITO electrodes 44, such as by athermal process conducted at about 500° C.-600° C. for about 30 minutesto about 120 minutes in air, N₂, or He gas (as non-limiting examples oftemperatures, times and atmospheres). The photoresist layer 40 can beremoved during the firing of the ITO ink and/or with other techniquessuch as, but not limited to, wet removal by a solvent or solution, or byuse of a UV ozone removal technique. Removal of the photoresist layer 40also serves to lift-off any fired ITO material that exists on thesurface of the photoresist layer 40, thereby leaving only the ITO finelectrodes 44.

Note also that in this embodiment that the planar electrodes, similar tothe electrodes 18 as in FIG. 5, can be deposited prior to the depositionof the photoresist layer 40, and the fin electrodes 44 can then besubsequently formed upon the planar electrodes.

The various fabrication methods described in relation to FIGS. 4-8,i.e., nano-imprinting, lithography and etch, lithography and lift-off,can be used as well to fabricate other configurations of electrodes forLCDs.

FIG. 9A shows an exemplary fin electrode 50 as fabricated by theprocesses of either FIG. 4 or 5. The fin electrode has a core 52comprised of PPLK or some other photo-patternable material orphoto-shielding material. Over the core 52 is the layer 54 of electricalconductor, such as ITO. FIG. 9B shows a variation on this structurewhere the fin electrode sidewalls are tapered so as to enhance thecoverage of the fin electrode sidewalls with the conductor layer 54. Ascan be seen, at least one sidewall of the fin electrode 50 is disposedat other than 90° to the surface of the substrate 10. FIG. 9C showsseveral further variations that beneficially increase sidewall coveragewhile also providing a larger aperture ratio. Note in the embodiments ofFIG. 9C that only one tapered sidewall and the top of the fin electrode50 is covered with the conductive layer 54. The vertical sidewallprovides a horizontal field and reduces the area of the fin electrode50.

FIG. 10A shows the arrangement of fin (inter-digitated, both pixel andcommon) electrodes 50 all formed on the same substrate 10 as in FIGS.9A-9C with the conductor-coated core 52. Alternatively the finelectrodes 50 could be formed of high aspect ratio conductors and couldbe implemented using any of the processes of FIGS. 6-8. In addition, anyof the fin electrodes 50 can include the underlying planar electrodes 18as was shown in FIG. 5. In FIG. 10B there is shown an embodiment wherethe negative (−) fin electrodes 50 are formed on the substrate 10 andpositive (+) fin electrodes 50 are formed on an opposing substrate 11(pixel electrodes on one substrate and common electrodes on the othersubstrate). In this case, and comparing to FIG. 10A, it can be seen thatthe horizontal field is not perfectly horizontal. FIG. 10C is a top viewof the fin electrodes 50 of either FIG. 10A or 10B, where it can be seenthat the fin electrodes 50 can have a basically chevron or other desiredshape, e.g., a zig-zag shape, to form multiple domains. The pixel andcommon electrodes can be either on one substrate or on two substrates.The fin electrodes 50 can be used in the IPS mode.

FIG. 11 shows an example of a fringe field switch (FFS) mode LCD. Inthis case the common electrode (−) is a planar electrode 60 disposedbeneath the pixel (+) fin electrodes 50 and separated by a dielectriclayer 10A. The pixel electrodes can be high aspect ratio fin electrodes50 to enhance the electric field and control of the liquid crystaldirector. The use of this embodiment can provide a higher fringe field,faster switching times, a wider viewing angle and a highertransmittance.

FIG. 12 shows an embodiment where the fin electrode 50 is used in theMVA mode. In FIG. 12A (top view) and FIG. 12B (side view) a combinationof the fin electrode 50 and the planar electrode 18 can be seen. In thisembodiment the common electrode (−) 60 is disposed on the uppersubstrate 11 and the fin electrode 50 (pixel electrode (+)) structure iscombined with the planar electrode 18. The planar electrode 18 can beused as either a pixel electrode or a common electrode, or as boththroughout the LCD. The fin electrode 50 structure can be one ormultiple structures located on or in the vicinity of a pixel. Theoverall shape/geometry of the fin electrode 50 and the planar electrode18 can be semi-spherical, ridge, cross (as shown), star or otherpatterns.

FIG. 13 shows an embodiment the fin electrode 50 and the planarelectrode 18 are used in an electrically controlled birefringence (ECB)mode of operation. In this exemplary case the fin electrode structurecombined with the planar electrode structure (in the exemplary crosspattern as in FIG. 12) can be used as either pixel electrodes, or commonelectrode, or both. In FIG. 13A (side view, V=0) and FIG. 13B (sideview, V≠0) a combination of the fin electrode 50 and the planarelectrode 18 on the substrate 10 with an opposing electrode 60 on thesubstrate 11 can be seen. As in FIG. 12, the fin electrode 50 structurecan be one or multiple structures located on or in the vicinity of apixel, and the overall shape/geometry of the fin electrode 50 and theplanar electrode 18 can be semi-spherical, ridge, cross, star or otherpatterns. The fin structure can be on either one or both electrodes.

One or more auxiliary electrodes within a pixel, which can be either afin electrode 50 and/or a planar electrode 18, can be employed as asub-pixel that can be used for precise control of the LC director. FIGS.14A and 14B show two different examples of shapes of the combined finelectrode 50 and planar electrode 18, where FIG. 14A shows the crossshape (as in FIGS. 12 and 13) and FIG. 14B shows an “X” shape. FIG. 14Cshows examples of auxiliary electrodes 70 that can be used with eitheror both of the shapes of FIGS. 14A and 14B (or other shapes/geometriesof the fin electrode 50 and the planar electrode 18). The auxiliaryelectrodes can be either on the pixel (as in the auxiliary electrode70A), at the periphery of the pixel (as in the auxiliary electrodes 70B)or in between pixels (as in the auxiliary electrode 70C). The auxiliaryelectrodes 70 can assume any two-dimensional or three-dimensional shape.The auxiliary electrode(s) 70 can be electrically connected to the mainelectrodes or they can be operated separately from the main electrodes.

It is noted that the various embodiments of the fin electrodes 50, withor without associated planar electrodes 18 and/or auxiliary electrodes70, can be used with a blue phase liquid crystal (BPLC) mode, andinter-digitated electrodes can be on one or two substrates.

As should be apparent the exemplary embodiments of this inventionprovide in one aspect thereof methods for forming a fin electrodestructure in an LCD. In addition to the presence of the optional planarelectrode 18 deposited in the plane of the substrates 10/11, anelectrode positioned in between the two substrates provides additionalcontrol of the electrical field within the LC cell to maximize thecontrol of the liquid crystal directors throughout the LC display forenhancing image quality. One example of this type of electrode is thefin electrode 50. The fin electrode 50 can have dimensions of forexample, a width of about 100 nm and a height of about 1 μm protrudinginto the LC cell (e.g., the height to width ratio may be about 10, orless than 10, or greater than 10). One advantage of the use of thisinvention is an enhancement in the precise control of the LC directorthroughout LC display to improve the image quality.

As should be further apparent the exemplary embodiments of thisinvention provide in another aspect thereof a LCD with non in-planeelectrodes, where the height of the non-planar electrode is comparableto or larger than the width of the electrode where some significantportion of the electrode extends out of the plane of the substrate toprovide a modification to the electric field generated by one or moreassociated planar electrodes.

As should be further apparent the exemplary embodiments of thisinvention provide in another aspect thereof the use of aphoto-patternable material, such as PPLK material, that can serve asboth a photoresist material and as a permanent on-chip insulator, afterpatterning and curing. In one process high aspect ratio structures areformed by patterning PPLK material utilizing a single exposure process.After patterning of the PPLK material, the patterned PPLK material canbe converted into a permanent patterned on-chip material by curing. Athin film electrode is coated onto the PPLK structure and other featuresto form pixel electrodes.

In an embodiment the PPLK fin structure is formed first, ITO issputtered on top of the PPLK fin structure, and then patterning isperformed to form fin electrodes 50.

In an embodiment the PPLK fin structure is formed first, ITO sputteredon top ITO is sputtered on top of the PPLK fin structure, and thenpatterning is performed to form fin electrodes 50 and planar electrodes18.

In other embodiments fin electrodes 50 can be formed by the use ofnano-imprinted ITO ink, or by the use of a thick ITO film that isdeposited followed by lithography and an RIE to pattern the ITO, or bythe use of a layer of photoresist that is deposited followed bylithography and an RIE or a liftoff process. A trench fill with ITO inkor some other suitable conductor can be accomplished to form the finelectrodes 50.

In some embodiments the sidewalls of the fin electrodes 50 can beoptimized in increase sidewall coverage with the electrical conductor aswell as to achieve a larger aperture ratio. Optimization of the sidewallcan include tapering one or more sidewalls of the fin electrodes 50.

In some embodiments the fin electrodes 50 are used in the IPS mode andinter-digitated electrodes, both pixel and common electrodes, are on thesame substrate.

In some embodiments the fin electrodes 50 are used in the IPS mode andthe inter-digitated electrodes, pixel and common electrodes, are ondifferent substrates.

In some embodiments the fin electrodes 50 are used in the IPS mode andthe inter-digitated electrodes take a chevron shape or a zig-zag shapeor some other shape to form multiple domains, where the pixel and commonelectrodes can be either on one substrate or on two substrates.

In some embodiments the fin electrodes 50 are used in the FFS mode andthe common electrode is beneath the pixel electrodes, separated by adielectric layer, where the pixel electrodes are high aspect ratio finelectrodes 50 to enhance the electric field and control of the LCdirector.

In some embodiments the fin electrodes 50 are used in the MVA mode wherethe fin electrode 50 structure is combined with one or more planarelectrodes 18 used as either pixel electrodes, or common electrodes, orboth. The fin electrode 50 structure can be one or multiple structureslocated on or in the vicinity of pixel. The overall shape can be, forexample, semi-spherical, a ridge, a cross, a star or other patterns.

In some embodiments the fin electrodes 50 are used in the BPLC (bluephase liquid crystal) mode, where inter-digitated fin electrodes can beon one or two substrates.

In some embodiments the fin electrodes 50 are used in the ECB(electrically controlled birefringence) mode, where the fin electrode 50structure combined with one or more planar electrodes 18 are use aseither pixel electrodes, or common electrode, or both. The fin electrode50 structure can be one or multiple structures located on or in thevicinity of pixel. The overall shape can be, for example,semi-spherical, a ridge, a cross, a star or other patterns. The finelectrode 50 structure can be on either one or both substrates.

In some embodiments the auxiliary electrodes 70 can be employed. Theauxiliary electrodes 70 can be either a fin electrode structure or aplanar electrode structure and can function as a sub-pixel that canprovide enhanced control of the LC director. The auxiliary electrodes 70can be located at one or more of: on the pixel, at the periphery of thepixel, or between pixels. The auxiliary electrodes 70 can take any 2D or3D shape and can be electrically connected to the main electrodes or canbe operated separately therefrom.

It should be appreciated that the various examples of the electrodesdescribed above are amendable to being fabricated as a part of anintegrated circuit either alone or in combination with other components,such as those found in displays for portable handheld devices such ascommunication devices, displays for computers, and displays fortelevisions.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present invention has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the invention. Theembodiment was chosen and described in order to best explain theprinciples of the invention and the practical application, and to enableothers of ordinary skill in the art to understand the invention forvarious embodiments with various modifications as are suited to theparticular use contemplated.

As such, various modifications and adaptations may become apparent tothose skilled in the relevant arts in view of the foregoing description,when read in conjunction with the accompanying drawings and the appendedclaims. As but some examples, the use of other similar or equivalentsemiconductor fabrication processes, including deposition processes,etching processes may be used by those skilled in the art. Further, theexemplary embodiments are not intended to be limited to only thosematerials, metals, insulators, dopants, dopant concentrations, layerthicknesses and the like that were specifically disclosed above. Any andall such and similar modifications of the teachings of this inventionwill still fall within the scope of this invention.

1-15. (canceled)
 16. A method to fabricate electrodes for a liquidcrystal display, comprising: providing a substrate having a surface;coating the surface with a dielectric material; patterning thedielectric material to form a plurality of upstanding first electrodestructures each having a height that exceeds a width; coating theupstanding first electrode structures and the substrate surface betweenupstanding first electrode structures with an electrically conductivematerial; and removing the electrically conductive material from betweentwo adjacent upstanding first electrode structures so as to retain aportion of the electrically conductive material upon the substratesurface thereby forming substantially planar second electrode structuresindividual ones of which are electrically continuous with theelectrically conductive material that coats an associated upstandingfirst electrode structure.
 17. The method as in claim 16, where thedielectric material is comprised of a photo-patternable low dielectricconstant material, and where the electrically conductive material iscomprised of indium-tin-oxide.
 18. The method as in claim 16, where atleast one sidewall of each upstanding first electrode structure isdisposed at other than 90° to the substrate surface.
 19. A method tofabricate electrodes for a liquid crystal display, comprising: providinga substrate having a surface; depositing a first layer comprised of anelectrically conductive material on the surface; depositing a secondlayer comprised of photoresist on the first layer; selectively removingfirst portions of the second layer to leave second portions, each secondportion being located at a position where an electrode is to be formed;and removing those portions of the first layer underlying the secondportions of the second layer, and removing the second portions of thesecond layer, leaving on the surface upstanding first electrodestructures each having a height that exceeds a width.
 20. The method asin claim 19, further comprising an initial step of forming planarelectrodes on the surface located at the positions where an electrode isto be formed such that each upstanding first electrode structure iselectrically continuous with one of the planar electrodes.
 21. Themethod as in claim 19, where the electrically conductive material iscomprised of indium-tin-oxide.
 22. A method to fabricate electrodes fora liquid crystal display, comprising: providing a substrate having asurface; depositing a layer comprised of photoresist on the substratesurface; opening apertures through the layer to expose the substratesurface at locations corresponding to positions where an electrode is tobe formed; filling the apertures with an electrically conductivematerial; and removing the layer of photoresist leaving on the surfaceupstanding first electrode structures comprised of the electricallyconductive material, each upstanding first electrode structure having aheight that exceeds a width.
 23. The method as in claim 22, furthercomprising an initial step of forming planar electrodes on the surfacelocated at the positions where an electrode is to be formed such thateach upstanding first electrode structure is electrically continuouswith one of the planar electrodes.
 24. The method as in claim 22, wherethe electrically conductive material is comprised of indium-tin-oxidethat is subjected to a thermal process.